Wisconsin From Orbit: How Landsat Watches Its Crops, Lakes and Cities

Beer brewed with lake water and chilled with lake ice; cheese from dairy pastures; the Dells, Door County and the Northwoods — much of what Wisconsin is known for comes straight from its land and water. The Landsat satellites, which have photographed the Earth's surface continuously for 50 years, help the state keep track of all of it.

A state of resources

Four ways Landsat helps

Mapping crops and land cover

Crop monitoring was one of Landsat's first uses and is still one of its biggest: it feeds the U.S. Department of Agriculture's annual Cropland Data Layer, which helps predict yields and food supply. The Wisconsin Department of Natural Resources, with the University of Wisconsin–Madison and the State Cartographer's Office, used Landsat imagery from 2010–2014 to replace its 1990s land-cover map. The result, Wiscland 2, is detailed enough for work national databases cannot support — species management, watershed planning, fire risk, property management.

Wisconsin's land cover. The dominant crops by acreage are corn, soybeans, hay, wheat, oats and rye. U.S. Department of Agriculture

Watching lake water

For more than 20 years the DNR has used Landsat to assess its lakes more cheaply and quickly than boats alone could: tracking water clarity on thousands of lakes, spotting changes in quality, detecting harmful algal blooms that endanger people and animals, and seeing how changes on land affect the water. Volunteers in the Citizen Lake Monitoring Network measure clarity on the ground, which calibrates what the satellites see.

An algal bloom on the eastern side of Lake Winnebago, Landsat 8, June 26, 2016. U.S. Geological Survey

Measuring urban heat

Pavement and buildings hold heat, so cities run hotter than the land around them — enough to cause heat illness and deaths. Studies usually focus on big cities; University of Wisconsin researchers instead looked at Madison, a mid-sized city ringed by farmland, using eight summers of ground sensors and archived Landsat temperatures to see when and where its heat island forms, and how much the surrounding cropland's temperature varies over a growing season (Berg and Kucharik, 2021).

Madison, the state capital, where researchers compared urban and farm temperatures. Ron Przysucha, U.S. Department of State

Landsat, nationally

• The most widely used land-imaging data in federal civilian agencies — and used by local, state and Tribal governments and by business every day, like GPS and weather data.
• Free to everyone, worldwide, through the USGS EROS Center, funded by the National Land Imaging Program.
• Landsat 8 and 9 together image all of Earth's land every 8 days; NASA and the USGS are designing Landsat Next to continue the record.
• Worth an estimated $2.06 billion a year to the U.S. economy (2017 study; Straub and others, 2019) — far more than it costs to build and run.

Sources

Written from Wisconsin and Landsat, U.S. Geological Survey Fact Sheet 2022–3055; a work of the United States government in the public domain. It cites the USDA (2021, 2022), the Wisconsin DNR (2016, 2022), Berg and Kucharik (2021), and Straub and others (2019).